I was born with one kidney and could never remember which so when I went in for an ultrasound of my bladder I asked to find out which kidney I have. I have my left kidney. They noticed within the interpolar region, there is an 11x8x9mm hypoechoic lesion probably reflective of a small cortical cyst, although there are some low level internal echoes which I suspect are artifact they suggest to have a followup ultrasound to ensure stable appearance. they added that no additional renal lesions, calculi or hydronephrosis identified Please tell me what this means in simple terms and should I be worried of kidney cancer, failure or anything else bad!